1. Geogenic hexavalent chromium in arid and alkaline aquifers versus industrial plating sources
Households in LA served by Parish Water Company might notice a faint metallic taste or be curious about chromium-6, also called hexavalent chromium or chromium(VI), in their water. This form of chromium can occur naturally in groundwater, especially in regions with arid conditions and alkaline aquifers, where it is released from minerals into the water. Alternatively, industrial sources such as plating plants can contribute chromium-6, but for Parish Water Company’s system, EPA sampling from 2013 to 2015 does not indicate industrial contamination as a primary source.
2. How oxidation state changes between the well, the distribution main and the tap
Chromium can exist in several oxidation states, with chromium-6 (Cr(VI)) being one of them. Between the water source, the distribution mains, and your household faucet, the chemical environment can cause chromium to change forms. For example, reducing conditions underground or in plumbing can convert chromium-6 to chromium-3, which is less mobile and less likely to cause taste or aesthetic concerns. The Parish Water Company records show very low detections, suggesting limited chromium-6 presence in the distribution, but household plumbing and fixtures might further influence its form.
3. Which fixtures, appliances or processes are affected first and why
Chromium-6, even at very low levels, may interact with certain household fixtures differently. Appliances that use water for heating or aeration—such as water heaters, humidifiers, or refrigerator dispensers—may expose chromium-6 to conditions that change its form, potentially affecting taste or appearance. Faucets with aerators can also change the water’s chemistry slightly. Understanding these variations helps identify where chromium-6 impact might be first observed inside the home.
4. How to judge treatment capacity against the household's or facility's daily demand
To address chromium-6 concerns, households need to estimate their daily water use and select treatment equipment accordingly. The C-Series Chromium-6 Filter ships ready to configure for residential use, matching common household demand levels. Deciding on capacity involves considering peak water use times and fixture count to ensure effective treatment without excessive maintenance or flow restrictions.
5. How sample depth, well depth or source type changes what a reader should expect
Variability in chromium-6 levels can depend on source depth and well characteristics. Deeper wells in Parish Water Company’s area may access water with different redox conditions, altering chromium-6 presence. The EPA’s public water system record reflects aggregate results from multiple sampling points, so individual well depths or source types can influence a household’s water quality independently of the reported data.
The Parish Water Company system was monitored under EPA’s Unregulated Contaminant Monitoring Rule 3 from 2013 to 2015: 48 chromium-6 samples were taken, with only one detection above the reporting level of 0.03 micrograms per liter (µg/L) or parts per billion (ppb), measuring 0.039 µg/L. No samples exceeded any federal maximum contaminant level, and no health-based violations are recorded. This record covers the public water system’s supply and distribution, not individual homes.
For residents concerned about chromium-6, conducting a private water test is the only way to determine their specific household levels. The C-Series Chromium-6 Filter offers a documented technology option designed to reduce chromium-6 effectively when configured and maintained for household use. More information on water quality data is available at the EPA's official site.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2013-11-09. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Parish Water Company (LA1033019), LA: 96 results across 2 listed contaminants, 1 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L